In many processes there is involved the step of reacting a nongaseous material with a gaseous reactant to a produce gaseous product. In some reactions it is desirable to prevent the gaseous product from reacting with residual nongaseous material. This invention relates to an apparatus and method for reacting nongaseous material with a gaseous reactant and removing the gaseous product from the reaction zone before the gaseous product can react with nongaseous material.
For example, in many carbonization processes there is involved the step of heating nongaseous carbonaceous material by partial oxidation of a portion of the nongaseous carbonaceous material to produce a gaseous product containing carbon dioxide and gaseous H.sub.2 O. The partial oxidation is for purposes of heating the nongaseous carbonaceous material to a higher temperature for recirculation to the carbonization zone as a heat-supplying medium. In such processes it is desirable to minimize the reactions of carbon dioxide and gaseous H.sub.2 O with the nongaseous carbonaceous material, which produce carbon monoxide, because such reactions are endothermic and their occurrence will reduce the overall thermal efficiency. In order to minimize these reaction it is necessary that the gaseous products, carbon dioxide and gaseous H.sub.2 0, be immediately removed from the reaction zone.
This invention relates to a process for heating nongaseous carbonaceous material by partial oxidation of a portion thereof to release thermal energy which remains substantially with the residual portion thereof so as to produce a heat-supplying medium.
This invention also relates to an apparatus for heating nongaseous carbonaceous material by partial oxidation of a portion thereof to release thermal energy which remains substantially with the residual nongaseous carbonaceous material, and for the immediate separating of the gaseous product from the nongaseous carbonaceous material.
In the past, processes involving a heating of nongaseous carbonaceous material by partial oxidation have suffered a loss of thermal efficiency caused by the reaction of the gaseous product, which contains carbon dioxide and possibly gaseous H.sub.2 O, with the nongaseous carbonaceous material to produce carbon monoxide. Because the formation of the carbon monoxide from the reaction of the gaseous product comprising carbon dioxide and possibly H.sub.2 O with the carbon content of the remaining nongaseous carbonaceous material is endothermic, useful heat is lost from the system.
Processes have been used in the past to reclaim some of the lost heat by burning the carbon monoxide. Although some heat may be recovered, the transfer of the heat released to the remaining nongaseous carbonaceous materials is not as efficient as the process of this invention which prevents the formation of carbon monoxide from the residual carbonaceous material.
Processes which employ the heating of nongaseous carbonaceous material by partial oxidation of a portion of the nongaseous carbonaceous materials are, for example, employed in pyrolysis processes. In many such processes, nongaseous carbonaceous material is employed as a heating medium by mixing the hot nongaseous carbonaceous material in direct heat transfer relationship with fresh nongaseous carbonaceous material to be pyrolyzed. High heat transfer rates are achieved by intimate contacting of the fresh feed material with heated char so that low residence times are achieved thereby enhancing the gaseous product yield and quality.
Pyrolysis processes are used to convert particulate carbonaceous materials such as coal, either coking or noncoking type, an agglomerative or nonagglomerative type to a valuable gaseous product and char. The char product often is heated separately by partial oxidation of a portion thereof to raise the remaining portion to a higher temperature. The heated char is then recycled to the pyrolysis zone to supply at least a portion of the heat required for pyrolysis.
Other carbonaceous materials employing the heating of a nongaseous carbonaceous material to a higher temperature to use as a heat-supplying medium are found in the pyrolysis of solid waste materials, such as municipal solid wastes and industrial solid wastes.